The Supreme Court argues that the right to abortion is up to the states to decide. At the same time, there's a very real fear that if Republicans take over Congress and the White House by 2024, they may attempt to pass a federal law banning abortion in the United States. It wasn't clear to me how Congress could enact such a federal law or—hypocrisy aside—what the Supreme Court might say about it. Isaac Chatiner presents a clear explanation in The New Yorker:
There are at least two bases on which Congress might enact a federal abortion ban. One would be under its power to regulate interstate commerce. Some of the conservative Justices have adopted a pretty limited reading of Congress's powers to regulate interstate commerce, but there could be some ways for a Republican legislature to write a statute that makes it more likely to be upheld on Commerce Clause grounds. Say [Congress] writes a statute that says, "No abortion can be performed if it uses any device that has travelled in interstate commerce or any medication that contains a component that has travelled in interstate commerce."
The second basis is that Congress might say, "We are enacting this legislation under our power to enforce Section 5 of the Fourteenth Amendment. We believe that fetuses are people. Therefore, we are enforcing and protecting fetal personhood and rights to life." Would the six conservatives conclude that Congress lacks the authority to enact either version of the statute, or reject both of those theories? I don't think we know. Chief Justice Roberts has taken more expansive views of Congress's power.